1. Field of the Invention
The present invention relates to a power supply apparatus and method for controlling same in a mobile communication terminal, and in particular, to a power supply apparatus and method for controlling a power supply voltage supplied therefrom where the power supply apparatus and method provide a reduction in size and an increase in power efficiency of the mobile communication terminal.
2. Description of the Related Art
A mobile communication terminal, such as a CDMA (Code Division Multiple Access) terminal and a GSM (Global System for Mobile communication) terminal, generally includes a rechargeable battery for providing the mobile communication terminal with a power supply voltage. A power supply apparatus connected to the rechargeable battery typically includes DC/DC converters for converting a DC voltage provided by the battery to several operating voltages for each part of the mobile communication terminal.
FIG. 1 illustrates a prior art power supply apparatus for a mobile communication terminal. The power supply apparatus down-converts (or steps down) a DC voltage of 7.2V provided from a battery 10 to a DC voltage of 3.9V for a receiver and baseband signal processor 30 and to a DC voltage of 5.0V for a transmitter and power amplifier 40. The prior art power supply apparatus includes a DC/DC converter 18 for converting the DC voltage of 7.2V supplied from the battery 10 to the DC voltage of 3.9V for the receiver and baseband signal processor 30, and a DC/DC converter 22 for converting the DC voltage of 7.2V supplied from the battery 10 to the DC voltage of 5.0V for the transmitter and power amplifier 40. The DC voltage output from the DC/DC converter 22 is provided to the transmitter and power amplifier 40 by way of a switch SW. The switch SW ensures that the converted DC voltage output from the DC/DC converter 22 is provided to the transmitter and power amplifier 40 only in a transmission mode and not in a reception mode. This reduces the power consumption in the reception mode. Hence, the mobile communication terminal reduces the overall power consumption and extends the life of the battery.
The prior art power supply apparatus as illustrated by FIG. 1 includes two DC/DC converters. Consequently, a reduction in size of the mobile communication terminal is compromised.
A need therefore exists for a power supply apparatus for a mobile communication terminal which has one DC/DC converter for providing a reduction in size of the mobile communication terminal.
Further, a need exists to provide a power supply apparatus and method for controlling a power supply voltage supplied therefrom in a mobile communication terminal for maximizing power efficiency of the mobile communication terminal and extending the life of a battery connected to the power supply apparatus.
A power supply apparatus for a mobile communication terminal is provided having voltage regulators, a receiver and baseband signal processor, a transmitter, a power amplifier, and a DC/DC converter for converting a DC voltage from a battery. In a reception mode of the mobile communication terminal, the power supply apparatus regulates the DC voltage converted by the DC/DC converter and supplies the regulated DC voltage to the receiver and baseband signal processor. In a transmission mode, the power supply apparatus converts the DC voltage converted by the DC/DC converter to a DC voltage corresponding to a transmission AGC (Automatic Gain Control) voltage which is determined based on a transmission power. The converted DC voltage is then supplied to the receiver and baseband signal processor, the transmitter, and the power amplifier via the voltage regulators.
The power supply apparatus has a single DC/DC converter and adaptively varies the output voltage of the DC/DC converter according to the transmission power in the transmission mode. Accordingly, the power supply apparatus of the present invention provides for a reduction in size of the mobile communication terminal. Further, the power supply apparatus of the present invention provides for a reduction in the amount of power loss by the voltage regulators and the power amplifier, thereby maximizing power efficiency and extending the life of the battery.
A method is also provided for controlling a power supply voltage in a mobile communication terminal capable of operating in a reception mode and in a transmission mode. The mobile communication terminal having a power supply apparatus including a receiver and baseband signal processor, a transmitter, a power amplifier, and a DC/DC converter. The DC/DC converter converts a DC voltage supplied by a battery. The method comprises the steps of regulating the DC voltage converted by the DC/DC converter and supplying the regulated DC voltage to the receiver and baseband signal processor in the reception mode of the mobile communication terminal; and converting the DC voltage converted by the DC/DC converter to a DC voltage corresponding to a transmission AGC (Automatic Gain Control) voltage determined according to a transmission power and supplying the converted DC voltage to the receiver and baseband signal processor, the transmitter, and the power amplifier in the transmission mode of the mobile communication terminal.